Authorities said the shooting at Saugus High School that left two students dead and three wounded occurred over a 16-second period in which a classmate pulled out a gun in the quad area and opened fire.

The gunfire broke out at 7:30 a.m., when students at the school were scheduled to be in their first-period classes, said Los Angeles County Sheriff Alex Villanueva.

Paramedics rushed onto the campus, treating the wounded, and law enforcement officers searched nearby neighborhoods for a 16-year-old boy they thought had fled after the shooting. Authorities later said the suspect, identified by neighbors and sheriff’s officials as Nathaniel Berhow, was found on campus with a self-inflicted gunshot wound to the head.

Officials said he was taken to a hospital and is in grave condition. Authorities said a message referencing the shooting, thought to have been posted before the attack, appeared on an Instagram account believed to be linked to the suspect. But Instagram said late Thursday, as first reported by BuzzFeed News, that the account didn’t belong to the teenager. A company representative said via email that the account has since been disabled “for violating our policies.”

Sheriff’s Capt. Kent Wegener said the teen was standing in the quad when he pulled a .45-caliber handgun from his backpack and opened fire on other students before turning the gun on himself. It was the suspect’s 16th birthday, authorities said.

What the f%$# is wrong with this country?